Iron Sight
Member
If both are available, why choose a soft lead bullet over a harder lead bullet.
Soft Lead vs Hard lead
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243winxb
Member
There is not reason to choose softer than 15 BHN if your bullets are sized to the correct diameter and using a good lube. But if you want to use up pure lead laying around, it can be blended in with harder alloys. 2% antimony is need to 900fps. 5% antimony 2%tin to 1400fps. Above 1400fps a gas check base bullet is need with Lyman #2 alloy or Linotype. PSI on the bullet base can also affect this. See Lee pressure chart here and also Alloy hardness chart photos. http://www.photobucket.com/joe1944usa
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Jim Watson
Member
If you are shooting at low pressure and velocity, the softer bullet will obturate - form to fit the barrel - and give a better seal. It will actually be less likely to lead foul the barrel than a hard bullet on a mild load. There is a formula that gives a suitable bullet hardness to chamber pressure relationship... if you know or can determine those numbers.
243winxb
Member
Soft Lead VS. Hard Lead Alloys
Obturate means to plug or seal. This is done using bullets sized to the correct diameter or .001" larger than bore groove diameter, per Lymans instructions. This process is call swaging. Swaging takes place with cast or jacketed bullets. If the PSI of the load is to high for the alloy used the bullet base will be deformed and leading will accrue. "Bumping Up" as some call it is not needed or wanted in modern firearms. Pure or very soft alloy bullets can skid when going down the barrel. The lands makes a wider groove in the bullet that allowes hot cast to get past the bullet base. This will cause leading and poor accuracy. The bulllet can also skid as its leaving the barrel as the bearing surface of the bullet coming in contact with the bore becomes less and less. However pure lead is said to work well in some blackpowder loadings.
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rcmodel
Member in memoriam
I disagree.
Bumping up is very desirable in revolvers. Especiall if the cylinder throats are larger then the bore.
The bullet must be soft enough to bump up to fill the chamber throats or gas cutting will cause leading.
The driving bands may actually melt before the bullets ever get to the forcing cone or rifling. Once gas cutting in the cylinder occurs, it will continue all the way up the barrel because the bullet "leaks" hot gas past the driving bands.
Hard bullets at low pressure are very likely to cause leading in a revolver with loose chamber throats.
rc
Bumping up is very desirable in revolvers. Especiall if the cylinder throats are larger then the bore.
The bullet must be soft enough to bump up to fill the chamber throats or gas cutting will cause leading.
The driving bands may actually melt before the bullets ever get to the forcing cone or rifling. Once gas cutting in the cylinder occurs, it will continue all the way up the barrel because the bullet "leaks" hot gas past the driving bands.
Hard bullets at low pressure are very likely to cause leading in a revolver with loose chamber throats.
rc
Six
Member
Here's a good 5 minute read, even though it's designed to sell their particular product:
http://www.missouribullet.com/technical.php
http://www.missouribullet.com/technical.php
243winxb
Member
Start with a larger diameter bullet in the first place.
Missouri Bullets doesn't even know what Lyman #2 alloy contains. http://www.thehighroad.org/showthread.php?p=5740258
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I agree with rcmodel on this one.
It is best to have bullets sized to about .001 over throat diameter, and hopefully that throat diameter is at or slightly (.001 to .0015) over bore diameter.
But even if this is true in your revolver, softer alloy, as long as it is tough enough to grip the lands and not skid down the barrel, is better than being too hard.
If the throats are .002 over bore diameter, or especially if it's even more than that, a softer alloy is better as well. It will easily bump up to fit the throats, and then swage back down to fit the bore easily as well.
In a perfect world our six revolver throats are all the same diameter, and are all just ever so slightly over bore diameter, which would enable us to use much harder bullets, but alas, it is not so, and many revolvers have throats that are too little or too big, and also vary within the same cylinder.
Softer bullets help with this real world reality, as long as they are tough enough to grip the lands at whatever velocity they are being shot at.
It is best to have bullets sized to about .001 over throat diameter, and hopefully that throat diameter is at or slightly (.001 to .0015) over bore diameter.
But even if this is true in your revolver, softer alloy, as long as it is tough enough to grip the lands and not skid down the barrel, is better than being too hard.
If the throats are .002 over bore diameter, or especially if it's even more than that, a softer alloy is better as well. It will easily bump up to fit the throats, and then swage back down to fit the bore easily as well.
In a perfect world our six revolver throats are all the same diameter, and are all just ever so slightly over bore diameter, which would enable us to use much harder bullets, but alas, it is not so, and many revolvers have throats that are too little or too big, and also vary within the same cylinder.
Softer bullets help with this real world reality, as long as they are tough enough to grip the lands at whatever velocity they are being shot at.
rcmodel
Member in memoriam
Witness soft lead .38 Spl Hollow-Base Wadcutters.
They don't get no softer then that, and they Obturate thier butts off!
They also never lead, and are the most uniformly accurate target bullet made.
The thing is, you have to match bullet hardness with the velocity /pressure of the load you want.
rc
They don't get no softer then that, and they Obturate thier butts off!
They also never lead, and are the most uniformly accurate target bullet made.
The thing is, you have to match bullet hardness with the velocity /pressure of the load you want.
rc
From the posted link: http://www.missouribullet.com/technical.php
Optimum BHN = CUPS / (1422 x .90)
There is another link, which is regularly cited at the forum
http://www.lasc.us/FryxellCBAlloyObturation.htm
It says:
Pressure (PSI) should be 3..4 * 480 * BHN
The two formulas do not match. The first one translates to
PSI should be 2.67 * 480 * BHN
Factor 2.67 is not in a range 3..4 of the second formula.
Any ideas why the formulas are different?
Optimum BHN = CUPS / (1422 x .90)
There is another link, which is regularly cited at the forum
http://www.lasc.us/FryxellCBAlloyObturation.htm
It says:
Pressure (PSI) should be 3..4 * 480 * BHN
The two formulas do not match. The first one translates to
PSI should be 2.67 * 480 * BHN
Factor 2.67 is not in a range 3..4 of the second formula.
Any ideas why the formulas are different?
GP100man
Member
this is how i was taught : fit first , then match speed to hardness of the boolit so it does`nt strip in the rifling, & a decent lube.
no set rules except it takes these conditions to shoot lead accurately & with minimum leading
GP100man
no set rules except it takes these conditions to shoot lead accurately & with minimum leading
GP100man
243winxb
Member
helg, the formula lists 10% less to give the working pressure to be used for a flat based bullet,SO THE BULLET DOES NOT OBTURATE.
Hardness in not everything. There must be Tin in the alloy when fps and pressures are above lite target loads.
Shoney
Member
The world according to SAAMI
OBTURATION
The momentary expansion of a cartridge case against chamber walls which minimizes the rearward flow of gases between the case and the chamber wall when the cartridge is fired.
The term obturation refers only to the case, not the bullet.
OBTURATION
The momentary expansion of a cartridge case against chamber walls which minimizes the rearward flow of gases between the case and the chamber wall when the cartridge is fired.
The term obturation refers only to the case, not the bullet.
rcmodel
Member in memoriam
floydster
Member
This is just too deep for me, I just lube with LLA load and shoot.
Never a problem.
Floydster
Never a problem.
Floydster
Shoney
Member
RC
Most of the last half of my reloading years. I thought obturation was only a term used for the bullet. Upon duscussion with a ballistics enginer, he corrected me with SAAMI definition.
There are some bullet types that do obturate, many of the hollow base bullets and air rifle pellets. The engineer stated that for the most part, there is no way a jacketed bullet or a hard cast bullet can obturate. Instead of depending on obturation, the oversizing of the diameter in lead bullets is what seals the bore. Some require 0.001 and some 0.002 or greater.
Most of the last half of my reloading years. I thought obturation was only a term used for the bullet. Upon duscussion with a ballistics enginer, he corrected me with SAAMI definition.
There are some bullet types that do obturate, many of the hollow base bullets and air rifle pellets. The engineer stated that for the most part, there is no way a jacketed bullet or a hard cast bullet can obturate. Instead of depending on obturation, the oversizing of the diameter in lead bullets is what seals the bore. Some require 0.001 and some 0.002 or greater.
Shoney
Member
Walkalong
Presuming that jacketed bullets do obturate, my understanding is that most, but not all, jacketed bullets are the same diameter as the intended bore. Then please explain how a 0.400 bullet or 0.450 bullet obturates in a bore of 0.400 or 0.450?
Why do lead bullets come 0.001 to 0.003 over bore so they seal? Are they expanding, or does the diameter remain the same and thus seals gas in the barrel bucause of being over size?
If there is obturation of the lead bullet, wouldn't a bore sized lead bullet do, rather than having an oversize bullet ot complete the seal?
Presuming that jacketed bullets do obturate, my understanding is that most, but not all, jacketed bullets are the same diameter as the intended bore. Then please explain how a 0.400 bullet or 0.450 bullet obturates in a bore of 0.400 or 0.450?
Why do lead bullets come 0.001 to 0.003 over bore so they seal? Are they expanding, or does the diameter remain the same and thus seals gas in the barrel bucause of being over size?
If there is obturation of the lead bullet, wouldn't a bore sized lead bullet do, rather than having an oversize bullet ot complete the seal?
243winxb
Member
Just Because its on the Internet, Does Not make it True or Correct
The link http://en.wikipedia.org/wiki/Obturate RC has posted can be changed/edited by anyone. Plus the information has not proven to be accurate.
The link http://en.wikipedia.org/wiki/Obturate RC has posted can be changed/edited by anyone. Plus the information has not proven to be accurate.
Login and change the information anyway you want. Taking measurements of .177" Match Grade Pellets show the also Swage into the barrel on firing. The nose measures .178" At the skirt .184" Measuring some old Star HBWC, the mic at .358" the will also swage on firing. The reason for a hollow base design is a weight forward bullet of this type, moving slowly is more accurate, just like shotgun slugs.
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Jim Watson
Member
An increasingly common misnomer, seldom mentioned, but at least as important as the Internet Expert Expostulation on clip versus magazine.
The bore diameter is measured to the tops of the lands, the hole size bored (and reamed) before the rifling grooves are cut. No modern bullets are of bore diameter. The US approach to jacketed bullets is to make them to nominal groove diameter. As Bart B has pointed out, there is some use of oversize bullets, his example in British .308 target rifles. There is also a mostly European school of thought that the bullets should be slightly smaller than groove diameter to give the metal displaced by the lands someplace to go.
But bullet bump-up to obturate in order to seal the barrel and engage the rifling was well understood in the 19th century and is being relearned by BPCR shooters. They started out paper patching bullets up to groove diameter to imitate jacketed bullets, but the trend is to the old way of a well undersized bullet patched to bore diameter or only a thousandth more.
Obviously the bullet will not expand/obturate over bore diameter.
You answered yourself, so they will seal the bore well.
Oversized is best. That is a proven fact. Even when a smaller lead bullet obturates/expands (or whatever one wishes to call it) to seal the bore or cylinder, there is a small amount of time where it does not and some flame cutting can still occur. better to start slightly oversized than under, or even at bore diameter.
To think a lead bullet, even a hard cast, heat treated one, can withstand the pressures of being fired without expanding to completely fill the bore, at some of the pressures they are fired with, is incredulous to me.
Most jacketed bullets are a soft copper jacket filled with dead soft lead. They will expand under the pressures they are subjected to as well.
something vague
Member
I've shot a ton of different brand lead bullets with different hardnesses (not sure if that's a word) to them in my revolvers. I have always got leading and thought that was just part of shooting these things. It wasn't until recently that I finally decided to try the softest swaged bullets I could find thinking that I was going to be cleaning some more lead out. To my extreme surprise I was amazed that I got much better accuracy than hard cast bullets and couldn't find a lick of leading in one of my loads. Specifically a 148gr. HBWC made by Hornady (you may have seen my post about this load with Trailboss). Since then I have become an advocate for soft lead. In all of my shooting I have always assumed that hard cast bullets would cause less leading, therefore always buying the hard cast bullets to shoot. But I still spent insane amounts of time at the bench cleaning lead out of my bores. Luckily I just took the dive into soft swaged lead bullets.
Maverick223
Member
So for a 100% hard lead (clip on wheel weight) projectile pushed to about 1600-2000fps I will need gas checks? I thought that they were only need with a softer lead composition.
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